Another word meaning "cool" or "hip". A combination of the words 'sick' and 'tight'. It is used when a person can't decide whether to use sick or tight to describe something that has happened, ergo, they use "sicktight."
Other expansions of the word include "super sicktight" and many others.
"Dude, that party last night was sicktight!"
"I know man it was awesome."
Something that is cool or something that blows your mind.
Jimmy: Dude, I just saw the craziest thing in my life.